This invention relates generally to non-linear conduit or piping systems which house, protect and seal from the environment electrical wiring systems and, particularly to curved joints used to join pipe segments together to allow the pipe to be disposed at some angle, usually 90 degrees, and more specifically to a pipe elbow which includes a plurality of rollers disposed along the inside curvature portion of the elbow so that an electrical wiring conductor, it is needs to be changed or removed, can be easily and quickly disposed around the corners in the piping system.
In many permanently mounted piping systems such as galvanized metal or aluminum pipes, it is impossible to remove the pipe in sections once installed. Such pipes have been traditionally used to house and protect cables, electrical wire, or other types of conductors within the pipe in a sealed environment such as chemical and petrochemical plants which frequently experience an explosively hazardous atmosphere. Oftentimes, however, it also becomes necessary to remove the electrical conductors or install new ones within the piping system. Great difficulties have been experienced in the installation and removal of electrical conductors from permanently mounted piping systems that include one or more elbow joints which may be of 90 degrees (or other angles) because of the frictional force on the electrical conductors relative to the interior surface when trying to negotiate the angle or corner joint in the piping system. Although there are other roller-type elbows available, none will safely function in an explosive atmosphere, to prevent strong internal electrical arcing from escaping from the elbow into that atmosphere or to prevent explosive gases from entering the piping system through the roller elbow.
The present invention greatly eliminates the problem of installation or removal of electrical conductors from a permanently mounted piping system around elbow joints (including 90 degree pipe joints) by providing a plurality of permanently mounted rollers which may be formed and mounted within an integrally formed elbow joint while maintaining the explosion-proof integrity of the piping system, thus meeting the most stringent Article 501, Class 1, Div. 1 and definition Article 100 requirements of the national electrical code.